Weakened tissue, especially bone, can cause multiple complications if it can not bear a certain threshold of weight. For example, compression fractures of the spine are a common, painful and debilitating complication of osteoporosis or neoplastic diseases of the vertebral bodies. In many patients, the pain is very severe and patients are unable to bear their own weight. This can require prolonged bed rest, which is known to lead to further complications including pneumonia, thromboembolism, muscle-decay, and further bone demineralization. In addition to being painful and debilitating, compression fractures of vertebral bodies also typically result in a loss of vertebral height along the anterior margin of the involved vertebrae. This leads to an anterior wedge deformity that causes the kyphosis. Patients having compression fractures of the spine are generally treated by a procedure called percutaneous Vertebroplasty.
Common Vertebroplasty procedures involve drilling into a vertebral cavity, removing tissue from within the cavity, and then delivering polymethylmethacrylate (PMM) cement or other physiologically acceptable binding material into the body of the fractured vertebra. For example, US 2007/0197861 to Reiley teaches using a rotatable loop and cutting blade to sever the tissue, and then uses a rotatable brush or a suction tube to remove material within a bone before adding PMM cement. US 2008/0009875 to Sankaran teaches using expandable, rotatable blades which are used to sever the interior tissue, but then injects a liquid into the cavity before sucking out the tissue. The process of removing the severed tissue can cause further trauma to the patient, and could cause the walls of the cavity to compress and seal, decreasing the areas where the PMM could interdigitate with the uncut tissue walls.
Reiley, Sankaran, and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Other methods of restoring a vertebral height involve inflating a balloon within the cavity, or using another object to push against the cavity walls to restore a vertebral height. U.S. Pat. No. 6,676,665 to Foley teaches a surgical instrument that pushes against the interior of a cavity wall to restore a vertebral height. Such compression techniques, however, also cause the walls of the cavity to seal, decreasing the areas where injected PMM could interdigitate with the uncut tissue walls.
In view of the current state of the art, there is still a need in the art for tissue surgery apparatus and methods for reinforcing weakened tissue.